Dedham deals with infiltration and inflow issues in sewer system

By Caitlyn McGoff, dedham@wickedlocal.com

Monday

Apr 8, 2019 at 4:00 PM

When clean water enters a sewer pipe, it joins with the existing flow and is treated unnecessarily, which increases sewer costs.

At a public meeting held Monday, April 1, Town Engineer Jason Mammone presented an overview of infiltration and inflow, and explained what it meant for the town and how it could be dealt with going forward.

According to a handout given at the meeting, infiltration is “clean water from below the ground that enters sewer pipes through cracks,” while inflow is “rainwater that enters sewer pipes through a mistake in the piping or from homes that direct rainwater to the sewer pipe instead of the drain pipe.”

Dedham’s wastewater is treated at the Massachusetts Water Resources Authority plant. Because of I/I, water that does not need to be treated enters into the pipes and is also transported and treated by the MWRA. I/I may cause sewer flooding, and the cost to treat I/I may be more than $2 million per year.

According to the presentation, 48 percent of what the town pays to the MWRA for treatment is for I/I.

Mammone said the main impact I/I has on Dedham residents is the additional cost of treating water that should not be in the pipes. On the presentation screen, a video showed the inside of a pipe with wastewater running through it. Gesturing to the video, Mammone pointed out the area in which clean water was entering the pipe. In some clips, the incoming water was a small trickle, while in others a clear stream gushed into the pipe. He added that the town has been manually inspecting public and private sewer lines to catch I/I, and have already made some repairs to public lines.

“A lot of our major leakers we have taken care of,” he said.

However, the issue of I/I into private sewer lines is a more complicated matter. Mammone said that so far in the town’s inspections, 62 private service connections were confirmed to have infiltration. When a private line is found to have infiltration, Mammone said the resident is notified, and the infiltration source must be removed. This process can consist of the pipe being cured-in-place or being dug up and replaced.

Currently, it is the responsibility of the homeowner to cover the cost of I/I repair on his or her property. The town is responsible for any I/I that occurs on the street. At the meeting, Mammone and other representatives, including Board of Selectmen member Michael Butler, asked attendees for input on who should be responsible for covering the costs of repairing private sewer lines and what the process should be to cover those costs. The price tag of these repairs could range from $5,000 to $20,000, per Mammone. Mammone said one option would be for the town to establish a reimbursement fund from the sewer budget to offset some of the cost from the property owner.

Butler said the pipes in the town are old, with some of them dating as far back as the 1930s, which leaves residents open to issues in the future.

“If you don’t have a problem [with I/I] this year, maybe in the next five years you’ll have a problem,” he said. “Right now the policy is clear. The individual property owner is responsible for fixing the pipe.”

He added that the meeting was designed to solicit public input for the process and determine if and how the current policy should change. The audience was asked to vote on a series of questions, including who should be responsible for covering the cost of repairing a private sewer line; how long should be given to complete the repair; if there should be a financial penalty for not completing the work on time; and how much should be paid from the sewer fund if that option was available; and what options homeowners should have for repaying the sewer fund.

When surveyed, only a small percentage of attendees felt the property owner should be responsible for paying for 100 percent of the repairs, while 45 percent said the cost should be paid by the sewer enterprise fund, and 48 percent said the cost should be shared between the fund and the property owner.

Almost half of the audience also said the sewer fund should pay more than 50 percent of the cost if shared between property owners and the fund.

Mammone said the engineering department would seek additional input from residents, and a focus group would be formed to assess the topic. The Board of Selectmen would then hear a presentation regarding the topic, and Butler said he hoped the board would be able to make a decision on any changes by the end of the year.

For more information, visit www.dedham-ma.gov/departments/engineering/sewer-system/inflow-and-infiltration-i-i.